The effect of gas permeability of film dressings on wound environment and healing.

We have determined the effect of oxygen and carbon dioxide permeability of thin film dressings on wound exudate P O2, P CO2, pH, and epithelialization in shallow wounds on domestic pigs. Three kinds of films were compared: polyvinylidine chloride, a low gas permeability film; polyurethane, a medium gas permeability film; and poly(dimethyl silicone), a high gas permeability film. Exudate under the silicone film had the highest P O2 and the lowest P CO2; exudate under the polyurethane had intermediate P O2 and P CO2; and exudate under the polyvinylidine chloride had the lowest P O2 and highest P CO2. Values for pH under the films correlated inversely with P CO2. The gas tensions and pH are a reflection of the ability of the films to control the diffusion of oxygen into and the loss of carbon dioxide from the wound exudate. Mean epithelialization values at 2 and 3 d were not significantly different under polyvinylidine chloride and polyurethane, but both were higher than under the silicone film. We infer from the data that the use of oxygen and carbon dioxide impermeable film dressings do not affect epithelialization in well-perfused, shallow wounds. The use of the silicone film (highly permeable to both oxygen and carbon dioxide) led to a loss of carbon dioxide. The resulting relatively high pH may have been responsible for the reduced rate of epithelialization which occurred beneath the silicone film.